Building integrated photovoltaic system with glass photovoltaic tiles

ABSTRACT

Building integrated photovoltaic (BIPV) systems provide for solar panel arrays with improved aesthetics and efficiency that can replace a conventional roof surface structure. These BIPV systems can utilize photovoltaic PV roof tiles defined as glass tiles having photovoltaic elements embedded or incorporated into the body of the roof tile. Such PV roof tiles can include one or more lapping features for interfacing with adjacent tiles and features for electrically connecting multiples tiles within a course to an external power optimizer. Such PV roof tiles can utilize stamped glass that is stamped to define these features within an integrated glass tile and can further include texture, striations on the glass tile and/or color matched back layers or various other components to obscure visibility of any embedded solar cells and provide a more pleasing appearance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/662,241, filed Jul. 27, 2017, which claims the benefit of priority ofU.S. Provisional Application No. 62/413,893, filed Oct. 27, 2016, theentire contents of which are incorporated herein by reference in theirentirety.

This generally relates to U.S. Non-Provisional application Ser. No.15/399,712, filed Jan. 5, 2017; the entire contents of which areincorporated herein by reference in their entirety for all purposes.

TECHNICAL FIELD

This generally relates to photovoltaic systems, and in particularbuilding-integrated photovoltaic roof tile systems.

BACKGROUND

Solar is becoming increasingly popular in the United States and abroad,but penetration remains relatively low versus the number of homes thatcould benefit from solar. The price per kilowatt for solar is nowcompetitive with or below that of fossil fuel-based utility power inmost areas, however, solar largely remains a niche product for those whovalue saving money, reducing CO₂ emissions, or both.

One factor that may limit the adoption of solar technology isaesthetics. Most residential solar systems are installed as modules overan existing tile or composition shingle roof. The solar array, whichoften only covers a portion of the roof, or even a portion of onemounting plane on the roof, stands out as separate and distinct from theexisting roof, both in height and material. This structure is thereforevisible even from the street level and over large distances.

Another obstacle to solar adoption in existing homes is the dissonancebetween the age of the existing roof and the solar system, particularlywhere the existing roof is made from composition shingles. The expectedlife of a solar system can be 25 years or more, and the expected life ofa composition shingle roof is also about 25 years, depending on thelocal climate and specific tile materials, however, at the time acustomer is considering going solar, their existing roof may be severalyears, if not decades, into that lifespan. So the customer may bepresented with the dilemma of getting a new roof first, increasing thecost of going solar, or installing a 25+ year solar system on a roofwhich may have a relatively shorter remaining operational lifespan.

Accordingly, there is a need to resolve the dissonance between theexpected life of the solar system and the remaining life of the roof,and for photovoltaic systems that blend in more aesthetically with thecomplete roof surface or at least the mounting plane, and that do notrequire the prospective customer to pay for a new roof and a new solarsystem installed on top.

BRIEF SUMMARY

Building integrated photovoltaic systems utilizing glass solar rooftiles are described herein. Such solar roof tiles allow for improvedaesthetics that more closely resemble conventional tiled or shingledroofs and allow the system to replace much of the conventional roofsurface structure. In addition, some aspects allow for improvedefficiency, ease of installation and manufacturing. These and otherembodiments are discussed in greater detail in the detailed descriptionand drawing figures.

In one aspect, the invention provides a photovoltaic (PV) roof tile thatincludes one or more solar cells, a planar glass member overlaying theone or more solar cells, and a substrate supporting the one or moresolar cells within a cavity and affixed to the planar glass member so asto encase or encapsulate the one or more solar cells therein. Each PVroof tile further includes electrical contacts that are electricallycoupled with the one or more solar cells and are accessible from anexterior of the planar glass member and substrate affixed thereto. Insome embodiments, the electrical contacts are disposed within aconnector disposed along an up-roof portion of the PV roof tile that isconfigured to be accessible from an up-roof direction for connectionwith a corresponding connector when the respective PV roof tile ismounted on or within the roof. In some aspects, mounting on the roof canentail placement or mounting on a roof substrate and/or mounting of thePV roof tiles on battens or cross battens. Typically, the up-roofportion having the connector would reside beneath an adjacent up-roofcourse of PV roof tiles or ridge cap tiles when installed within theroof assembly. In some such embodiments, the PV roof tiles lack anyelectrical connector on the lateral side portions and/or underside ofthe PV roof tiles, which further improves ease of installation andweatherproof engagement between laterally adjacent PV tiles within acourse. Such embodiments can include an electrical cable or harnesselectrically coupling adjacent PV roof tiles within a string via theabove-described connectors. The cable or harness can reside above eachcourse of PV roof tiles underneath the adjacent up-roof course ofshingles or cap tiles along a ridge. In some embodiments, each PV rooftile includes a lapped region along one lateral side dimensioned tounderlie an adjacent PV roof tile when installed within a course. EachPV roof tile may further include a textured surface, such as ridges orstriations, on or under the top glass surface, that visually obscure theunderlying solar cells. In one aspect, the texture is defined so thatthe one or more solar cells encapsulated within the PV roof tile arevisually obscured, either partly or fully, when viewed from a non-normal(e.g. less than or greater than 90 degrees) viewing angle.

In another aspect, each PV roof tile includes wire bussing electricallyconnected to the one or more solar cells and extending to the electricalcontacts. Each PV roof tile includes an up-roof portion over which anup-roof course of like PV roof tiles are overlaid when mounted in asolar roof tile assembly, and a down-roof portion in which the one ormore solar cells are disposed and that remains exposed when mounted inthe solar roof tile assembly. This portion may be referred to as the“reveal portion.” In some embodiments, electrical contacts are disposedwithin one or more connector portions in the up-roof portion of the PVroof tile. The electrical contacts can be disposed in a connector alongan up-roof edge of the PV roof tile and configured to electricallyconnect with a corresponding connector in a wiring harness, the harnessextending adjacent the up-roof portions of adjacent solar roof tileswithin a course.

In some embodiments, each PV roof tile includes a junction box or otherelectrical contact disposed on opposing lateral sides thereof, eachbeing configured to electrically connect with a corresponding electricalcontact on an adjacent solar roof tile in a solar roof tile assembly(e.g., V+ to V−, V− to V+). Such electrical contacts could include anyof: exposed wires, metal tabs, a female connector, and a male connector.

In still other embodiments, each PV roof tile can include electricalcontacts disposed in a connector portion on an on underside of the solarroof tile, each being configured to electrically connect with a busbarwithin a mounting track configured for mounting on a roof. Suchembodiments can utilize any of various connectors that can bothmechanically and electrically coupled PV roof tile to the busbar track,typically by inserting and twisting the connector into the track.

In another aspect, each PV roof tile includes one or more solar cellsand a planar glass member overlaying the one or more solar cells, wherethe solar cells are encapsulated beneath the planar glass member by oneor more underlayers. The one or more underlayers can include a firstlayer adjacent the one or more solar cells and a second layer underlyingthe first layer. The first and second layers can be the same ordifferent materials. In some embodiments, the layers are made fromethylene vinyl acetate (EVA), in others, polyolefin or a polyvinylmaterial. Typically, both layers adjacent the cell are the samematerial.

In another aspect, building integrated photovoltaic systems areprovided. Such systems can include PV roof tiles that are electricallyconnected together in a string when arranged within a first course on aroof surface. Such systems can further include a first wire bussingelectrically connected to each of the PV roof tiles, and a firstoptimizer coupled with the wire bussing. In some embodiments, the firstwire bussing between the first course of PV roof tiles is configured forcarrying low voltage. The system can further include a high voltagewiring electrically connected to the optimizer for carrying a highvoltage DC or a high voltage AC to a main panel of a building on whichthe system is installed. In some embodiments, the system includes afirst plurality of PV roof tiles electrically connected by a first wirebussing connected to a first optimizer and a second plurality of PV rooftiles electrically connected by a second wire bussing connected to asecond optimizer. In some such embodiments, the first and secondpluralities of PV roof tiles can include first and second courses of PVroof tiles that overlap. In another aspect, the wire bussing can includea wiring harness having a number of taps for connecting to respective PVroof tiles of the plurality and terminating in the first optimizer. Insome embodiments, the wire bussing can be defined as a busbar track. Insome embodiments, the system can further includes a wiring harnesshaving a number of taps and terminating in a DC optimizer, the number oftaps limiting the aggregate voltage of all connected PV roof tiles to anamount less than 50 volts.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative aspects of the present disclosure are described in detailbelow with reference to the following drawing figures. It is intendedthat that embodiments and figures disclosed herein are to be consideredillustrative rather than restrictive.

FIG. 1A shows an example of a BIPV system having PV roof tiles,according to some embodiments.

FIG. 1B shows a detail view of two courses of PV roof tiles electricallyconnected with a power harness, according to some embodiments.

FIGS. 1C and 1D show examples of textured patterns in a top surface of aglass face of PV tile to obscure visibility of solar cells within whenviewed at an angle, according to some embodiments.

FIG. 2A shows conventional photovoltaic panels mounted on a roof.

FIG. 2B shows a conventional photovoltaic panel.

FIG. 3 shows an exploded view of a PV roof tile for use in a buildingintegrated photovoltaic system, according to some embodiments.

FIGS. 4A and 4B show detail views of a top glass tile and supportsubstrate, respectively, of a PV roof tile, according to someembodiments.

FIGS. 5A-5C show a power optimizer/wiring harness for use with a stringof PV roof tiles, according to some embodiments.

FIG. 6 shows a circuit diagram for wiring a string of PV roof tilesaccording to some embodiments.

FIGS. 7A-7B show a custom power optimizer/wiring harness for use with astring of PV roof tiles, according to some embodiments.

FIGS. 8A-8C show detail views of an alternative embodiment of a PV rooftile, according to some embodiments.

FIG. 9 shows an exploded view of the alternative PV roof tile embodimentshown in FIGS. 8A-8C.

FIG. 10 shows a system having multiple courses of PV roof tileselectrically coupled with a central inverter, according to someembodiments.

DETAILED DESCRIPTION

The present disclosure describes various embodiments of photovoltaicroofing systems, in particular PV roof tiles, systems and associatedmethods. Some embodiments relate to building integrated photovoltaicmodule assemblies and associated systems and methods. In variousembodiments, the systems described herein lower costs of conventionalsystems in which a PV system is installed over a roof, and at the sametime can provide an improved aesthetic for a PV roof system, andparticularly a building integrated PV system.

Certain details are set forth in the following description and in theFigures to provide a thorough understanding of various embodiments ofthe present technology. Other details describing well-known structuresand systems often associated with PV systems, roofs, etc., however, arenot set forth below to avoid unnecessarily obscuring the description ofthe various embodiments of the present technology.

Many of the details, dimensions, angles and other features shown in thefigures are merely illustrative of particular embodiments. Accordingly,other embodiments can include other details, dimensions, angles andfeatures without departing from the spirit or scope of the presentinvention. Various embodiments of the present technology can alsoinclude structures other than those shown in the Figures and areexpressly not limited to the structures shown in the figures. Moreover,the various elements and features shown in the figures may not be drawnto scale. In the figures, identical reference numbers identify identicalor at least generally similar elements.

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” uniform in height to another object would mean that theobjects are either completely or nearly completely uniform in height.The exact allowable degree of deviation from absolute completeness mayin some cases depend on the specific context, however, generallyspeaking, the nearness of completion will be so as to have the sameoverall result as if absolute and total completion were obtained.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given value may be “above”or “below” the value. For example, the given value modified by about maybe, for example, by ±5%, ±10%, ±15%, ±20%.

Wherever used throughout the disclosure and claims, the term “generally”has the meaning of “approximately” or “closely” or “within the vicinityor range of”. The term “generally” as used herein is not intended as avague or imprecise expansion on the term it is selected to modify, butrather as a clarification and potential stop gap directed at those whowish to otherwise practice the appended claims, but seek to avoid themby insignificant, or immaterial or small variations. All suchinsignificant, or immaterial or small variations should be covered aspart of the appended claims by use of the term “generally”.

As used herein, the term “building integrated photovoltaic system” or“BIPV” generally refers to photovoltaic systems integrated with buildingmaterials to form at least a portion of a building envelope. Forexample, the BIPV system can form the roof or roofing membrane of abuilding. The BIPV systems described herein can be retrofitted, can be apart of a new construction roof, or a combination of both. Such buildingintegrated photovoltaic structures can be alternatively referred to asbuilding integrable photovoltaic (“BIP”) or building appliedphotovoltaics (“BAPV”). Components of a BIPV system used, in part, asthe actual building envelope (e.g., roofing membrane), can provide awatertight or substantially watertight seal for the roof surface.Alternatively, BIPV systems may merely look like they are part of theroof even through there are other roofing materials making up thebuilding envelope installed below such BIPV systems.

For the sake of distinguishing between structural elements of thepresent BIPV system, as used herein, the terms “photovoltaic module”,“PV module”, and “solar cell” refer to the structures of the system withsolar energy collecting elements, while the term “PV roof tile” refersto such solar collecting elements as mounted or adhered to, or locatedwithin a structural roof tile. Accordingly, as used herein, a “rooftile” refers to a structural element of a roof, which may or may nothave PV elements attached thereto, depending on the context of thedescription.

As used herein, the terms “up-roof” and “down-roof” are used to provideorientation, direction, position, or a reference point relative to or incontext of a roof or roofing surface upon which the systems describedherein are installed on and/or form a portion of. Up-roof generallyrefers to an orientation that is relatively closer to the roof ridgewhile down-roof refers to an orientation that is relatively closer tothe roof eave.

As used herein, the singular forms “a”, “an”, and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “includes”and/or “including”, when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as shown in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, term such as “below” can encompass both anorientation of above and below, depending on the context of its use. Thedevice may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used herein areinterpreted accordingly.

Although the terms “first”, “second”, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,it should be understood that they should not be limited by these terms.These terms are used only to distinguish one element, component, region,layer, or section from another region, layer, or section. Thus, a firstelement, component, region, layer, or section discussed below could betermed a second element, component, region, layer, or section withoutdeparting from the teachings of the present invention.

As used herein, the terms “and/or” and “at least one of” include any andall combinations of one or more of the associated listed items.

Rapid shutdown devices (“RSD”) for PV systems can be applied to thesystems described herein, and can be located or positioned in variouslocations. In some embodiments, a recess or other opening can be made instructural support pans (e.g. a transition pan or a non-PV pan) throughinsulation such that RSD can be inset or positioned inside recessedopening. Vents can be positioned on top of opening to conceal or coveropening. Structural support pans can be elements of roofing frames orarray systems that provide stability or integrity to the overallstructures, as described in further detail below. RSD can be positionedwithin a box or other suitable container prior to positioning withinrecess. In other embodiments, RSD can be positioned under eaves, or eaveflashings or gutters. In yet other embodiments, RSD can be positionedwithin attic portions of a building.

Generally, PV modules are made with crystalline-based solar cells, whichcan be either or both of monocrystalline cells or polycrystalline(multi-crystalline) cells. The laminate or wafer forming the solarenergy-collecting surface of such PV modules can be mechanicallycoupled, adhered, or bonded to structurally supporting tiles. In someembodiments, PV modules can include layers of amorphous silicon or thinfilm variations of solar energy-collecting laminates, or thin-film solarmaterials directly applied as continuous sheets. Generally, PV rooftiles as considered herein, which can include PV modules, solar cellsand laminates, have individual structures that can be used incombination to form larger solar arrays and/or building structures, asset forth below. Alternatively, thin-film PV modules, such as cadmiumtelluride, copper-indium-gallium-diselenide (“CIGS”), or amorphousthin-film silicon may be used. In still further embodiments, cells basedon perovskite or other as of yet non-commercialized materials may beused. The particular type of cell technology used for any giveninstallation can be selected both for solar energy collectingfunctionality and for aesthetic qualities, as related to the presentdisclosure.

For any given solar panel installation on the roof of a residential,commercial, or industrial building, there is a balance obtained betweenthe power generation of the solar panel array, the visual appearance andaesthetic of the solar panel array, and the structural requirements formounting or constructing the solar panel array. For BIPV installationsas considered herein, the materials for forming the roof and the PVelements for collecting solar radiation are combined into a single unit,where the aesthetic of the solar panel array can be optimized whilestill maintaining a desired level of power collection and generation.However, not every surface, slope, or region of a roof may be amenableto, or need to be used for, solar energy generation. Thus, BIPV systemscan also include “dummy” or “mimic” roof tiles or simply “roof tiles”that can include patterning or silicon elements that appear similar tothe PV roof tiles, but do not collect solar radiation and are notelectrically interconnected to each other or other PV system components.

PV elements that are distributed over all roof surfaces can have avisual uniformity that is neat, generally continuous, and elegant.Adjusting the density of PV element on a roof surface changes both theappearance of the overall roof and the energy production of the solararray on the roof, typically measured in kilowatts (kW) orkilowatt-hours (kWh). Accordingly, the density of PV elements can beadjusted to achieve a desired kilowatt-hour production goal whilemaintaining an even distribution of the PV elements with a consistentvisual aesthetic. In some aspects, PV elements can be distributed on thesurface of a roof in a randomized, semi-randomized, or non-regularpattern to achieve the aesthetically pleasing neat, generallycontinuous, and elegant appearance.

Tile Roof Building Integrated Photovoltaic Array

As discussed herein, solar cells that are integrated as part of rooftiles can be connected together and laid down so as to define the mainsurface of a roof, and in particular, a tile roof. By integrating solarcells into individual PV roof tiles, or clusters of PV roof tilescarrying solar cells so that the PV is part of the roof, advantages canbe obtained in comparison to more traditional “on-roof” arrays that areelevated above the surface of a roof. For example, roof surfaces formedof PV roof tiles are directly built onto the framing structure of a roofcan be lighter than on-roof installations, at least because the built-inBIPV solar array does not require a second structure above an existingroof. Further, a roof that is being replaced in a re-roofinginstallation can replace older or traditional roof tiles or with PV rooftiles, which can be more efficient in reducing the amount of materialsneeded for a re-roofing installation. Also, electrical connections,junction boxes, and wiring can be generally housed underneath PV rooftiles of BIPV assemblies, protecting such components from precipitation,wind, and excess heat, and further hiding such components from anobserver so as to make the overall BIPV system visually attractive oruniform.

Makers of BIPV solar systems generally aspire to provide for anadvantage over traditional on-roof PV systems by having a less drastictopological difference, thereby reducing visually noticeable differencesin height on regions of the roof. However, previous implementations ofBIPV systems do not necessarily provide for further visual qualities ordesign that effectively minimize noticeable differences between solarmaterials and standard roofing materials that form the overall PVsystem. Embodiments of the present disclosure provide for a BIPV system,with solar cells contained within individual roofing tiles andelectrically connected in strings or other circuits, which is visuallyappealing at least in that the solar elements and roofing materials arecombined and assembled in a layout that minimizes or camouflages thedifferences between the solar components and the standard constructionmaterials.

One advantage of the present system is that the process of laying suchPV roof tiles and making the necessary electrical connections between PVroof tiles is simpler than installing an entire tile or shingle roof andthen installing solar over the roof. A BIPV roof tile roof as consideredherein is mounted in generally the same manner as a standard tile roof,for example: securing and sealing underlayment or other sheathing toframe elements of the roof, adding battens as needed to portions of theroof frame, installing tiles to form the main surface of the roof,working around obstacles (e.g., chimneys, skylights, vents, etc.) asneeded, and installing ridge and edge tiles in combination with flashingor other trim structures of the roof. In the present system, the rooftiles must have a structural integrity capable of accommodating andsupporting PV elements on the tiles, in terms of weight, heat generated,ability to connect electronics, and retaining strength to serve as aportion of a roof surface. The tiles used can be of standard sizes asknown in the industry. Further, tiles used for systems considered hereincan have a wide range of colors to match or blend with PV elements,including, but not limited to, blue, blacks, grays, browns, and claycolorations.

FIG. 1A shows exemplary BIPV system 100 installed as part of a roofsurface. BIPV system 100 is composed of PV roof tiles 1 laid inhorizontal rows or courses on the roof surface. Vertically adjacentcourses of PV roof tiles 1 are offset from each other by about half thewidth of each roof tile 1, such that seams or breaks between twovertically adjacent rows of roof tiles 1 do not form a single seam orbreak along the full slope of roof surface. PV roof tiles 1 can beinstalled on the major planar faces of the roof as well as minor planarfaces, such as the gable shown in FIG. 1A. While PV roof tiles 1described herein allow solar cells to be installed on an increasedsurface area of the roof, as compared to conventional over-roof solarapproaches, there are typically some areas where PV roof tiles cannot beinstalled, such as at the ridge R, the hips H and the valleys V of theroof. In these areas, system 100 may incorporate use of “dummy” tiles orbasic roof tiles that resemble and ideally match PV roof tiles 1 inappearance to create a more uniform consistent appearance of the roof.These non-PV areas can be utilized for other purposes such as to coverelectrical components of the PV power generation system or to cover apower harness or return cables extending from each string of PV tiles.

As shown in FIG. 1A, PV roof tiles 1 are each defined in a rectangularshape so as to resemble conventional shingled or tiled roofs. It isappreciated that such tiles can be formed in various other shapesincluding, but not limited to: rectangular, square, club, step,bullnose, fishtail, arrow, curved, or irregular shapes, and may consistof more than one tile section and more than two solar cells 30.Generally, roof tiles considered for use herein are flat tiles forforming roofing structures, but in other embodiments roof tiles caninclude, but are not limited to: curved tiles, barrel tiles, s-shapedtiles, Spanish tiles, tiles shaped for the edges of a roof, or tilesshaped to interlock with adjacent tiles, or any other desired shape.

PV roof tiles 1 described herein include a layer of glass overlaying oneor more solar cells, which are encased by a substrate made of glass orother suitable material and/or one or more backing layers. The layers ofglass can be stamped tiles that are stamped to define one or morefeatures or contours that facilitate assembly of the tile or to provideimproved aesthetics. For example, the glass can be stamped to define alapping region that interfaces with an adjacent tiles in a course, or todefine a cavity for receiving the solar cells. An outwardly facingsurface of the top glass tile can also be stamped to form a pattern ortexture, such as ridges or striations, that further obscure visibilityof any solar cells encased within and to provide improved aesthetics ofthe roof installed system 100. In some embodiments, stamped tiles areformed to have a size and weight similar to roof shingles.

While PV roof tiles 1 are described herein as being formed of glass withone or more encapsulated solar cells, it is appreciated that there aredifferent types of PV roof tiles that can be used in any of theconfigurations described herein. For example, such roof tiles can alsobe made of various other materials, such as stone, quartz, slate,granite, ceramics, concrete, porcelain, rigid shingle, clay, onyx, orreplica materials for the same.

FIG. 1B shows two photovoltaic tile courses 101, which are horizontalrows of PV roof tiles 1, each course electrically connected in a stringby a power optimizing harness 4. As can be seen, each photovoltaic tile1 includes an up-roof portion that is mounted to the roof and adown-roof portion in which the one or more solar cells are incorporated.As can be seen, the up-roof portion of photovoltaic tile 1 is covered bythe next up-roof course, which leaves a gap (not shown) in which wirebussing/power harness 4 for each course can reside and remain protectedfrom dirt and debris. In this embodiment, each PV roof tile 1 furtherincludes a lapped region along at least one lateral side, whichunderlays the adjacent tile. This feature interleaves adjacent PV rooftiles 1 allows system 100 to function as a traditional roof in sheddingwater, which allows system 100 to entirely replace conventional tiles orshingles. It should be appreciated that although shown and described asindividual tiles, each PV roof tile 1 may consist of two or moreindividual tile sections integrally formed as an N-tile module where Nis an integer equal to two or more. In such a case, the solar cellscontained within each tile section will include internal bussing so thatthe N-tile module can function in the same way as a conventional PVmodule with a V+ and V− terminal at each end from left to right. TheseN-tile modules may simply connect to one other to a harness 4 via asingle two-wire connection.

Other aspects of the roof surface can interface with BIPV system 100 toprovide further improvements in performance and aesthetics. For example,ridge flashing can include a ridge cap at the top of the resultant BIPVarray that is used for venting, heat dissipation, wire management, andto generally conceal and protect wires (e.g., conduits or cables) orother equipment (e.g., fans, vents, connectors, inverters, jumpers,home-run connections). Waterproofing components, such as liners or trim,can be set underneath or between PV roof tiles such that roof surfaceproperly functions as a roof to prevent water from entering thestructure of the building. BIPV system 100 can also include otherroofing components (e.g., flashings, gutters, vents, caps, covers,trims), for example, at eave flashing, hips, valleys, or sides of theroof.

In various embodiments, PV roof tiles 1, and non-PV roof tiles, canmounted as part of roof surface with other structural components to forma roof envelope of a building. Moreover, as discussed in greater detailherein, PV roof tiles supporting or embedded with one or more solarcells can be specifically configured to accommodate electrical junctionboxes, diodes or micro-inverters on each individual PV roof tile,located on the bottom surface (underside) of relevant roof tiles.Wiring, cables, and/or power buses to electrically connect PV rooftiles, and by extension solar cells on PV roof tiles, can stringtogether a plurality of PV roof tiles. To avoid physical conflicts withunderlying studs, rafters, joints, battens, buttresses, or otherinfrastructure of a roof, such electrical components can be attached tothe underside of PV roof tiles in locations to avoid physical conflicts.

In one aspect, PV roof tiles 1 utilize top glass 10 having surfaces thatare textured to obscure visibility of solar cells when viewed atnon-normal angles such as angle (a). As shown in FIGS. 1C and 1D, topglass 10 of PV tiles 1 is textured with a striated or ridged pattern 19a or with an irregular pattern 19 b, both of which can be defined tomimic the surface of materials associated with conventional roofingsurfaces (e.g. tiles, shakes, slates, shingles). In some embodiments,the textured surface is designed to obscure visibility of solar cellsencapsulated within PV tile, either partly or fully, when viewed at anangle less than or greater than normal (e.g. 90 degrees) from thesurface of PV tile. In some embodiments, the textured surface is definedto substantially or fully obscure visibility of solar cells encasedwithin PV tile when the viewing angle relative normal exceeds angle (a).In some embodiments, the textured design is defined for such an angle of80, 70, 60, 50, 45, 30, 20, 15 or 10 degrees from normal. Typically,such textured surfaces are designed to be obscured when the viewingangle exceeds 45 degrees from normal. While textured patterns havingridges or striations and irregular shapes are shown here, it isappreciated that such textured surfaces could be defined in accordancewith a variety of textures as desired in order to obscure solar cellsencapsulated within respective PV tiles. Alternatively, smooth top glassmay be used to achieve a more planar, monolithic visual effect.

In contrast with embodiments of the present disclosure, FIG. 2A shows aconventional PV array installed on pitched shingled roof. Theconventional PV array of FIG. 2A includes six solar panels 901 or PVmodules which, (though not shown in detail) are mounted on the roofusing one of various known rail-based or rail-free mounting systems, asare currently employed by solar installers, such as San Mateo,Calif.-based SolarCity Corporation.

FIG. 2B shows one type of conventional solar panel 901 in more detail.Solar panel 901 includes PV laminate 902, which with conventionalsilicon-based cells, consists of a silicon sandwich of p-doped andn-doped silicon layers, a top glass sheet protecting the laminate, and aback sheet that can include a plurality of layers—and rigid metal frame103, supporting PV laminate 902. Although shown as a unitary structure,such a laminate 902 may include a plurality of individual solar cellsthat are wired together to form a single unit under the top glass sheetof PV roof tile 1. In the example shown in FIG. 1B, frame 903 is agrooved frame with groove 904 surrounding the outer face of frame 903 onall sides. Grooved frame modules such as module 901 are manufactured andsold by SolarCity Corporation of San Mateo, Calif. In such a module,groove 104 serves as mechanism for attaching other mounting hardware(e.g., a leveling foot, an interlock) to join modules together and tosupport the modules over a roof surface. Those of ordinary skill in theart will appreciate that panel 101 may also have a plain, non-groovedframe. Non-grooved frames are typically interconnected to one anotherand connected to the roof using connectors that clamp down between thetop and bottom edges of the frame.

Although these types of framed PV modules achieve their structuralfunction, they are aesthetically suboptimal and have material usageinefficiencies. First, conventional PV systems, such as that shown inFIG. 2A, are typically installed over an existing roof, and not as partof the existing roof, essentially requiring redundant structure sincethe PV array will shield most of the portion of the roof that it isinstalled over. Second, conventional systems are deemed by some peopleto be unappealing, having a choppy, discontinuous, and/or extraneousaesthetic. Conventional PV modules usually come in one of two colors:blue, signifying a poly-crystalline silicon structure, and black,signifying a mono-crystalline silicon or thin-film structure. The metalframe portion can be painted black to help it blend in with the roofsurface, or it can simply be raw aluminum. Regardless of whether blue orblack modules are used, the difference between the look of the portionof the roof that is covered with solar panels and the remainder of theroof is generally quite dramatic. This contrast can be particularlynoticeable when a conventional PV array is mounted on a tile roof. As aresult, roofs that are partially covered with solar panels have anaesthetic contrast that can be seen from very far distances due to thedifference in reflectivity, elevation, height, and/or color betweenthese two very different surfaces.

A string of PV roof tiles can be electrically connected together as asubset circuit of roof surface to have a specific or desired number ofsolar cells as part of the subset. Such subset circuits can have aspecific number of solar cells to build to a desired voltage or kilowattproduction. For example, a subset circuit of electrically connected PVroof tiles can have four (4) solar cells, six (6) solar cells, eight (8)solar cells, ten (10) solar cells, twelve (12) solar cells, or anyinteger number of solar cells within or around that numerical range. Byextension, subset circuits can alternatively have more solar cells 206to build to higher voltage and kilowatt levels, for example having20-cell, 24-cell, 30-cell, 36-cell, 40-cell, 42-cell, 48-cell, 54-cell,56-cell, 60-cell, 70-cell, 80-cell, or 92-cell embodiments. Furtherembodiments can have PV roof tiles with other number-of-solar-cellembodiments above, below, or within the above-considered increments.Typical PV modules have between 60 and 72 cells and are connectedserially into strings having a combined voltage of up to 600 volts DC sodepending on the number of solar cells in each PV roof tiles, they maybe connected into subcircuits with additive voltages in the same range(i.e., <600 volts DC). The various embodiments of strings with differentnumbers of solar cells allows for flexibility in selecting PV roof tilesappropriate for any given system installation.

While such tiles could be installed on any planar roof surface, it isappreciated that it might not be desirable to install such tiles onevery planar surface of a given roof. For example, on a given building,the South face of the roof may receive the most incident solar energy,while the North face may not receive sufficient sunlight to justify theadditional cost of PV roof tiles (relative to non-PV roof tiles). Tooptimize the use of PV elements, solar tiles according to thosedescribed herein may be installed on a generally South facing roof,while roof tiles that are identical or similar in appearance but lackintegrated solar cells may be installed on the North facing roof tocreate a consistent design aesthetic. Thus, both the South and Northsides of roof surface will appear the same while overall costs ofmaterials can be reduced by using non-PV roof tiles wherever energyproduction will be lowest. Likewise, for some roof surfaces, regions ofroof surface may be occluded from consistent incident sunlight (e.g. dueto shade from a tree), and accordingly, an occluded portion of roofsurface can be covered with mimic PV roof tiles, in order to avoidwasted costs associated with installing PV roof tiles in the occludedportion of roof surface that will not generate power.

Various details of the PV roof tiles described above can be furtherunderstood by referring to the example PV roof tiles in the followingfigure descriptions.

FIG. 3 and FIGS. 4A-4B depict exploded views of exemplary PV roof tile1, which includes solar cell layer 30 (e.g. two solar cells) encasedbetween top glass 10 and substrate 20 along with various other internalcomponents to ensure that solar cell layer 30 remains encased within PVroof tile 1 while maintaining electrical connectivity from outside thePV roof tile 1 and to provide improved aesthetics. These internalcomponents may include wire bussing 12 and connector 12 a, siliconepotting compound 13 surrounding solar cell layer 30, and masking 11 thatoverlays the wire bussing. Masking 11, potting compound 13, and/orsubstrate 20 can be painted with solar cell-matched paint to minimizecontrast between solar cell layer 30 and surrounding components so as tofurther obscure the presence of the solar cells within PV roof tile 1.

FIG. 4A shows a detail view of exemplary top glass 10 for use in PV rooftile 1. Top glass 10 may include one or more fastener features in anup-roof portion to facilitate mounting of PV roof tile 1 to the roof. Inthis embodiment, the fastening features are defined as two hangerkeyholes 14 for receiving a screw, nail, or other mechanical fastener.Top glass 10 may further include lapping feature 15 on one lateral side,which is dimensioned to underlay an adjacent PV roof tile 1 wheninstalled in a course. These features can be formed in top glass 10 whenstamped or can be formed by any suitable processing means. Top glass 10can further include a pattern or texture (not shown) in the top surface,which can further obscure the visibility of solar cell layer 30 withinPV roof tile 1. Typically, top glass 10 is formed of tempered glassalthough it should be appreciated that various other types of glass maybe used.

FIG. 4B shows a detail view of substrate 20, which can be formed fromthe same glass material as top glass 10, a different type of glass (e.g.tinted, reinforced), or an entirely different material such as steel,aluminum, fiberglass, or metal alloy. The substrate can be stamped in asimilar size and shape as top glass 10 so as to fit together with topglass 10. Substrate 20 may include one or more fastening featurescorresponding to those in top glass 10, such as two hanger keyholes 24,and a lapping recess 25 dimensioned to receive corresponding lappingfeature 15. Top glass 10 and substrate 20 can be bonded, such as with anadhesive or potting compound, fused, or can fixedly secured together byany suitable means. Substrate 20 further includes cell cavity 23, whichis dimensioned to contain one or more solar cells along with wirebussing attached to the solar cells and potting compound to encase thesolar cell within. Substrate 20 further includes wiring channel 22dimensioned to provide a passage for wire bussing 12 extending fromsolar cell 30 to a connector 12 a accessible from an exterior of PV rooftile 1. Typically, connector portion 12 a is defined along the top edgeof the up-roof portion, however, in some embodiments, it would bedisposed on a back side of PV roof tile or one or both edges. In someembodiments, some PV roof tiles may include multiple redundantconnectors along different portions or edges so as to allow aninterconnected string of PV roof tiles to change directions.

In some embodiments, solar cell layer 30 described herein refers tocrystalline-type solar cells. However, solar cell layer 30 is notlimited to crystalline-type solar cell technology. For example, in otherembodiments, thin-film or amorphous solar (e.g., amorphous silicon) canbe used as laminate layers with certain embodiments described herein. Inyet further embodiments, hybrid crystalline and amorphous solar modulescan be used with various systems described herein. In other embodiments,other types of solar cells (e.g., non-silicon based semiconductors,partial silicon, non-crystalline, partial crystalline, organic,carbon-based, perovskite, cadmium-telluride, CIGS, dye sensitized,transparent luminescent solar concentrator, polymer, transparent cells)can be provided as part of solar cell layer 30.

FIGS. 5A-5C illustrate an exemplary power harness 40 for electricallyinterconnecting a string of PV roof tiles 1 and carrying power to a mainpanel of the building on which PV roof tiles 1 are installed. Harness 40includes a wire cable 42 having a series of connectors or taps 43configured to connect with corresponding connectors 12 a of eachindividual PV roof tile or PV roof tile module (N individual tilesections configured as an integral PV roof tile module) in a course. Insome embodiments, connectors 43 are spaced apart sufficiently to allowpre-connecting of harness 40 to PV roof tiles 1 before installation. Insuch embodiments, it is desirable for the distance between connectors tobe greater (e.g. 10%, 20%, 30%) than the required distance (e.g.distance between connectors 12 a in adjacent PV roof tiles in a course)to allow the installer sufficient clearance to move and install thetiles or to install a subsequent tile connected along harness 40 in asubsequent course (e.g. up-roof or down-roof course). Harness 40 canfurther include sealed DC power optimizer box 41, which can beconfigured for low voltage maximum power point tracking (MPPT) and canoptionally include a voltage boost and/or DC to AC power inverter. Sucha configuration allows for harness 40 to be configured for low voltage,while the power optimizer 41 provides high voltage (DC or AC) at itsoutput, which can then be carried to the main panel by high voltagepigtail cables 44. FIG. 5B shows a detail view of exemplary poweroptimizer box 41 and FIG. 5C shows a detail view of tile to harnessconnector 43. While in this embodiment, a female connector of aparticular type is depicted, it is appreciated that connector 43 canutilize various other types of connectors or connections as desired.

FIG. 6 is a circuit diagram showing system 100 including individual PVroof tile 2 1 connected to harness 40 according to some embodiments. Invarious embodiments, a diode 44 can be provided for each PV roof tile 1or can be included as needed.

FIG. 7A shows an alternative embodiment of power optimizer harness 40′which allows for use of conventional OTS power optimizer box 41′ suitedfor use in a high voltage line but used with a low voltage harness. Thisis made possible by a modified connector 45 that allows connection of alow voltage harness to two higher voltage connectors. This approachwould allow for use of a wider range of readily available poweroptimization boxes that would normally not be suitable for use with alower voltage application.

FIGS. 8A-8C illustrate an alternative PV roof tile 1′, which encasessolar cell 30 beneath top glass 10 without use of a rigid substrate andwithout requiring use of stamped glass to form additional features (e.g.lapping region). Similar to the embodiment above and as can be seen inthe exploded view of FIG. 9, this tile assembly includes glass tile 50,masking 51, wire bussing 52 and connector 52 a, underlap member 55,solar cells 30, encapsulation layer 60 (e.g. ethylene-vinyl acetate(EVA)) and a backsheet layer 61 (e.g. polyvinyl fluoride film). Theselayers replace the rigid substrate of previous embodiments. It isappreciated that while EVA and polyvinyl fluoride films are described,various other types of materials, or combinations of materials could beused in a like manner. In some embodiment, backsheet layers can have acolor, such as a non-white or dark color, to reduce glare and reducecontrast between solar cell 30 and underlying surfaces. It should beappreciated by those of ordinary skill in the art that although the PVroof tiles are shown throughout the figures as having only a pair ofsolar cells 30, such PV roof tiles 1 may consist of two, three or evenmore PV tiles clustered together into a single module containing 4, 6 orN solar cells, where N is an integer greater than 6. Such modificationsare within the spirit and scope of the invention.

FIG. 10 shows BIPV System 103 having multiple low voltage PV roof tilecourses 101 electrically coupled to central inverter 44. One challengeassociates with such systems is that optimizer input circuits must berated the same voltage as the output circuits (i.e. full stringvoltage). One manner in which this can be dealt with is to use plasticcasings and remove any grounded surfaces within the low voltage circuitarea (indicated in dashed lines). Any transition or combiner box,wireways, or various other components outside the dashed border can havegrounded metal parts. Thus, the inverter or any components carryinghigher voltages can be located outside the low voltage PV roof tilearea, such as on the ground or inside the building on which the PVsystem is installed. This avoids a high voltage rating for the PV rooftile area, thereby avoiding undue overregulation during installation.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the various embodiments of the invention. Further,while various advantages associated with certain embodiments of theinvention have been described above in the context of those embodiments,other embodiments may also exhibit such advantages, and not allembodiments need necessarily exhibit such advantages to fall within thescope of the invention. Accordingly, the invention is not limited,except as by the appended claims.

While the above description describes various embodiments of theinvention and the best mode contemplated, regardless how detailed theabove text, the invention can be practiced in many ways. Details of thesystem may vary considerably in its specific implementation, while stillbeing encompassed by the present disclosure. As noted above, particularterminology used when describing certain features or aspects of theinvention should not be taken to imply that the terminology is beingredefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific examplesdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed examples, but also allequivalent ways of practicing or implementing the invention under theclaims.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various examples described above can be combined to providefurther implementations of the invention. Some alternativeimplementations of the invention may include not only additionalelements to those implementations noted above, but also may includefewer elements. Further any specific numbers noted herein are onlyexamples; alternative implementations may employ differing values orranges, and can accommodate various increments and gradients of valueswithin and at the boundaries of such ranges.

References throughout the foregoing description to features, advantages,or similar language do not imply that all of the features and advantagesthat may be realized with the present technology should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present technology. Thus,discussion of the features and advantages, and similar language,throughout this specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages, and characteristics ofthe present technology may be combined in any suitable manner in one ormore embodiments. One skilled in the relevant art will recognize thatthe present technology can be practiced without one or more of thespecific features or advantages of a particular embodiment. In otherinstances, additional features and advantages may be recognized incertain embodiments that may not be present in all embodiments of thepresent technology.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the invention can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further implementations of theinvention.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof means any connection or coupling,either direct or indirect, between two or more elements; the coupling orconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, refer tothis application as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively.

Although certain aspects of the invention are presented below in certainclaim forms, the applicant contemplates the various aspects of theinvention in any number of claim forms. Accordingly, the applicantreserves the right to pursue additional claims after filing thisapplication to pursue such additional claim forms, in either thisapplication or in a continuing application.

What is claimed is:
 1. A photovoltaic roof tile comprising: a pluralityof solar cells comprising a first solar cell disposed at a first end ofthe photovoltaic rooftile and a second solar cell disposed at a secondend of the photovoltaic roof tile opposite the first end; a transparentmember overlaying the plurality of solar cells; a substrate supportingthe plurality of solar cells and affixed to the transparent member so asto encase the plurality of solar cells therebetween; a connectordisposed along an up-roof portion of the photovoltaic roof tile that isconfigured to be accessible for connection with a correspondingconnector from an up-roof direction when the photovoltaic roof tile ismounted on or within a roof and is accessible from an exterior of thephotovoltaic roof tile; and a wire bussing comprising a first leadelectrically coupling the connector to the first solar cell and a secondlead electrically coupling the connector to the second solar cell. 2.The photovoltaic roof tile of claim 1, wherein the connector is on anunderside of the solar roof tile, and electrically connected with abusbar within a mounting track configured for mounting on a roof.
 3. Thephotovoltaic roof tile of claim 1, wherein the substrate supports theone or more solar cells within a cavity.
 4. The photovoltaic roof tileof claim 1, wherein the transparent member is a planar transparentmember.
 5. The photovoltaic roof tile of claim 1, wherein the up-roofportion of the photovoltaic roof tiles is the portion of the roof tileconfigured to be positioned beneath an up-roof photovoltaic roof tile.6. The photovoltaic roof tile of claim 3, wherein the connectorcomprises a plurality of electrical contacts.
 7. The photovoltaic rooftile of claim 1, further comprising a lapped region on a lateral side ofthe substrate dimensioned to underlie an adjacent photovoltaic roof tileand is configured to prevent water from passing between the photovoltaicroof tile and the adjacent photovoltaic roof tile.
 8. The photovoltaicroof tile of claim 1, wherein an outside surface of the transparentmember has a pattern or texture that obscures visibility of the one ormore solar cells.
 9. The photovoltaic roof tile of claim 1, furthercomprising masking disposed between the wire bussing and the transparentmember that overlays and conceals the wire bussing.
 10. A buildingintegrated photovoltaic system, comprising: a plurality of photovoltaicroof tiles electrically connected in a string when arranged within acourse on a roof surface, each photovoltaic roof tile of the pluralityof photovoltaic roof tiles comprising: a plurality of solar cellscomprising a first solar cell disposed at a first end of thephotovoltaic rooftile and a second solar cell disposed at a second endof the photovoltaic roof tile opposite the first end; a transparentmember overlaying the plurality of solar cells; a substrate supportingthe plurality of solar cells and affixed to the transparent member so asto encase the plurality of solar cells therebetween; a connectordisposed along an up-roof portion of the photovoltaic roof tile that isconfigured to be accessible for connection with a correspondingconnector from an up-roof direction when the photovoltaic roof tile ismounted on or within a roof and is accessible from an exterior of thephotovoltaic roof tile; and a wire bussing comprising a first leadelectrically coupling the connector to the first solar cell and a secondlead electrically coupling the connector to the second solar cell. 11.The building integrated photovoltaic system of claim 10, furthercomprising an optimizer coupled with the wire bussing.
 12. The buildingintegrated photovoltaic system of claim 11, wherein the wire bussingbetween the plurality of photovoltaic roof tiles is configured forcarrying low voltage, the system further including: a high voltagewiring electrically connected to the optimizer for carrying a highvoltage DC or a high voltage AC to a main panel of a building on whichthe system is installed.
 13. The building integrated photovoltaic systemof claim 10, wherein the wire bussing and the connectors of theplurality of photovoltaic roof tiles are configured such that at leastsome of the plurality of PV roof tiles are electrically connected withinthe string when arranged within another course down-roof of the course.14. The building integrated photovoltaic system of claim 10, wherein thesubstrate supports the one or more solar cells within a cavity.
 15. Thebuilding integrated photovoltaic system of claim 14, wherein the cavityincludes a wiring channel dimensioned to provide a passage for the wirebussing.
 16. The building integrated photovoltaic system of claim 15,wherein a first end of the wiring channel opens into a central portionof one side of the cavity.
 17. The building integrated photovoltaicsystem of claim 16, wherein a second end of the wiring channel extendsto an edge of the substrate.
 18. The building integrated photovoltaicsystem of claim 10, wherein a first photovoltaic roof tile of theplurality of roof tiles comprises a lapped region positioned on alateral side of the first photovoltaic roof tile that underlaps a secondphotovoltaic roof tile of the plurality of roof tiles.
 19. The buildingintegrated photovoltaic system of claim 10, wherein the transparentmember of one of the photovoltaic roof tiles comprises an opening andthe photovoltaic roof tile comprises a fastener extending through thetransparent member securing the transparent member to the substrate ofthe photovoltaic roof tile.